1,721,019 research outputs found
A new approach to assess the influence of road roughness on driver speed behavior based on driving simulator tests
No full textVehicle speed is one of main parameters describing driver behavior and it is of paramount importance as it affects the travel safety level. Speed is, in turn, affected by several factors among which in-vehicle vibration may play a significant role. Most of speed reducing traffic calming countermeasures adopted nowadays rely on vertical vibration level perceived by drivers that is based on the dynamic interaction between the vehicle and the road roughness. On the other hand, this latter has to be carefully monitored and controlled as it is a key parameter in pavement managements systems since it influences riding comfort, pavement damage and Vehicle Operating Costs. There is therefore the need to analyse the trade-off between safety requirements and maintenance issues related to road roughness level. In this connection, experimental studies aimed at evaluating the potential of using road roughness in mitigating drivers’ speed in a controlled environment may provide added value in dealing with this issue. In this paper a new research methodology making use of a dynamic driver simulator operating at the TEST Laboratory in Naples is presented in order to investigate the relationship between the driver speed behavior on one hand, and the road roughness level, road alignment and environment, vehicle characteristics on the other. Following an initial calibration phase, preliminary results seem fairly promising since they comply with the published data derived from scientific literature
Capability of Italian existing bridges to resist the impact against safety barriers
No full textABSTRACT: The aim of this paper is to investigate whether bridges designed according to Italian Standards in place since 1962 may resist the impact loads measured during crash tests of real bridge barriers. Their capacity has been assessed comparing the strength of overhang decks with the maximum values of the internal forces calculated by FEM analyses. Results show that bridges according to the current standard are able to sustain almost all the loads due to impact only if the design values of the internal forces are calculated by a simplified method. On the contrary, the capability to resist of bridges designed according to previous standards depends on barrier containment level, design methodology, cross section considered, impact position, strategy adopted for the reinforcement and width of overhang deck. The results obtained can be used both to check existing bridges and to design the new one
Assessing Influence of Road Roughness on Driver Behavior: Exploratory Step Through Dynamic Driving Simulator
No full textRoad roughness represents a key parameter in pavement management systems as it affects
driver’s riding comfort, pavement performance and Vehicle Operating Costs.
Ride quality is related to in-vehicle vibration that, in turn, is dependent on the level of road
roughness, on the speed chosen by the driver and on the inertial and mechanical characteristics of
the vehicles. Several studies have highlighted that, under certain conditions, driver may be
induced to vary his speed in order to reach an acceptable in-vehicle vibration level according to
his subjective exposure threshold. In this paper, a further contribution on this issue is presented.
A dynamic driving simulator (DDS) employing a real car fixed on a 6 degrees of freedom motion
platform is currently operating at the TEST Laboratory in Naples. The DDS system is able to
reproduce most of the accelerations the occupants feel, in particular those arising from turning
and braking maneuvers and from dynamic interaction with pavement surface singular
irregularities. A team of researchers from University of Naples “Federico II”, Second University
of Naples, University of Cassino (and the Oktal Company) have improved the system allowing
the implementation of a module simulating vehicle vibrations induced by distributed
irregularities. In this paper, the development of the vibration simulation module and the results
from preliminary experimental calibration procedures are briefly reported. The initial outcomes
of the performed tests seem to fairly agree with similar published results derived from technical
literatur
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Modelling Behavior in a Route Choice Driving Simulation Experiment in Presence of Information
No full textModelling route choice decision making in Advanced Traveler information System (ATIS) contexts is still a crucial task. In particular, two main categories of variables can be identified in order to model travelers’ behaviors: the former may be defined as endogenous and are related to the experiment environment; the latter may be defined as exogenous (referring to the respondents involved in the experiment). This paper focuses on the analysis of exogenous variables. An experiment is carried out using a driving simulator, on a real route choice context (a sub-area of the urban network in the city of Naples, in the Campania Region) reproduced in a virtual reality. All data are analyzed by aggregate and statistical approaches to preliminarily investigate the correlations between some exogenous variables and the collected choices of drivers. Furthermore, collected observations have been modelled by applying the Structural Equation Model (SEM) approach to model the effect of information on switching behaviors
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